There are many situations where natural water supplies contain pollutants, such as clay, animal waste, industrial pollution and other sources of pollutants that either make the water appear unsafe for drinking or unpalatable. These include remote communities in isolated regions and hikers, travelers, campers and similar travelling in remote regions. Taking a full supply of safe drinking water is both costly and bulky.
There are also many situations where natural or man made disasters cause damage or destruction to the reticulated water supply such that, although there is an adequate amount of water available, it is generally polluted with sewer/septic overflow, decaying organic matter or other pollutants. Drinking such water could result in consumers becoming infected with cholera or any number of other water borne diseases. Not drinking such water would result in rapid death due to dehydration.
There are a number of known devices which seek to address the above problem, including: chlorine tablets (to disinfect the water); filters to remove the pollutant; and others. A disadvantage of chlorine is, even if it is added to the water, the resultant unappealing taste of the water means that it is not liked by the populace. Storing chlorine tablets is also difficult and they are not easily available for many situations. A disadvantage of many emergency filters is that they can only be used for short periods of time before they become clogged. A disadvantage of reusable filters that can remove most pollutants is that they can be expensive. Also, filters do not remove some pollutants like mercury, lead, arsenate and similar. Further, many so-called “emergency” filters do not remove some of the smaller clay particles and the filtered water still thus appears unpalatable to drink, even though it is generally safe.
It is an object of the present invention to substantially overcome, or at least ameliorate, one or more of the above disadvantages.
By way of further background, the process of coagulation has been successfully used in the industry to achieve good water treatment results. In that process, trivalent metals, usually aluminium and/or iron, are used for cleaning water. Their ions, Al+++ and Fe+++ respectively, are added to polluted water in the form of alum (aluminium sulphate) or ferric chloride. The metal ions bind with the pollutant and assist in removing the pollutant from the water, either causing it to sink to the bottom (settling ponds), float to the top (dissolved air flotation) or increase the size of the pollutants and allow them to be more easily filtered. Irrespective of the mechanism of removal, the use of these ions is wide spread in the water treatment industry. Chemical treatment of water is often not viable because it adds to the salinity of the water and the chemicals are quite hazardous.
In the process known as electrocoagulation, those same ions are added to the water electrolytically. In that process, sacrificial electrodes are placed in the polluted water and a voltage applied to them. This causes an electric current to flow between the electrodes, which releases some of the anode metal into solution via the reactions:Al−3e− gives Al+++  (1andFe−3e− gives Fe+++  (2
The electricity also produces a reaction at the cathode when the electrons leave the cathode and go into the water, which reaction is given by:2H2O−4e− gives 2(OH)−+2H2  (3
This reaction liberates hydrogen gas.
In view of the complexities of the reactions and the power requirements to treat large volumes of water, known systems of this type are connected to large power supplies and used to process large volumes of water, typically many cubic metres per day. The process requires strict monitoring of the parameters involved, without which the process will fail and the water will not be cleaned. While suitable for large applications, they are not suited for small, ‘first stage’ water treatment or for regions with very little funding capability.